Yes the outside air is for the combustion.
I am not really worried about warranty as this is a used furnace.
The gentleman I am planning on buying it off is telling me it is a a125 which is the predecessor to the a150. I spoke with keystoker and they told me this is the same furnace, although this used furnace has a 1400 cfm blower not the larger one you have. Apparently it is not the original blower. I guess my main questions are:
Can I run successfully run a 30' duct to the middle of my 10x16x16' trunk and have favorable results with the available space without a lot of noise?
I have about a 10"x 14" area to run a duct through my closet from basement to attic, is this enough? Also, can I do it with simple round duct? (probably not round, huh?)
I can run a cold air return as it sounds like this is a good idea.
Maybe I am thinking about it too much? I suppose dampers can fine tune the flow?
Ultimately, I love my two stokers but I am getting a little tired of feeding them and emptying ashes, plus I want to take advantage of my new ductwork. This is my rationale behind moving to a furnace. Well that and i like to tinker.
Thanks for any additional advice.